Research map / Point clouds / Shape and surface completion
LAM3D: Large Image-Point Clouds Alignment Model for 3D Reconstruction from Single Image
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LAM3D compresses point clouds into latent tri-planes with a point-cloud autoencoder, then trains three parallel diffusion UNets to align single-image DINO features to those tri-planes for high-fidelity single-image mesh reconstruction in about 6 seconds.
Problem
Single-image 3D reconstruction with large reconstruction models produces geometric distortions because 3D shape is ambiguous from one image and multi-view images from diffusion are inconsistent.
Approach
Use point-cloud-derived latent tri-planes (with SDF supervision on latent and reconstructed planes) as a 3D-aware target, and align image features to them with probabilistic diffusion using three parallel UNets, one per plane, rather than deterministic transformers or contrastive alignment like ULIP.
Key results
- On Google Scanned Objects, LAM3D reaches Chamfer Distance 0.0083, Volume IoU 0.6235 and F-Score 85.40%, beating the best baseline CRM (0.0094, 0.6131, 79.38%).
- Mesh generation takes about 6 seconds on one NVIDIA V100 GPU.
- On the ablation set, the latent tri-plane with SDF loss reaches CD 1.81e-4, versus 4.81e-4 for a flat vector latent and 35.23e-4 for ULIP-based alignment; parallel UNets reduce CD from 3.92e-3 to 2.59e-3 compared with a single UNet.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| use LAM3D instead of CRM | Single-image 3D reconstruction · Google Scanned Objects | Chamfer Distance: 0.0094 -> 0.0083 | Helped |
| use LAM3D instead of CRM | Single-image 3D reconstruction · Google Scanned Objects | Volume IoU: 0.6131 -> 0.6235 | Helped |
| use LAM3D instead of CRM | Single-image 3D reconstruction · Google Scanned Objects | F-Score: 79.38 -> 85.40 | Helped |
| replace a vector latent with a spatial latent tri-plane (ablation) | LAM3D point-cloud compressor · Objaverse 216-object evaluation | CD (× 10^4): 4.81 -> 1.95 | Helped |
| add latent SDF loss (ablation) | LAM3D point-cloud compressor · Objaverse 216-object evaluation | CD (× 10^4): 1.95 -> 1.81 | Helped |
| use parallel diffusion UNets rather than a single UNet (ablation) | LAM3D image-point-cloud alignment · Objaverse 216-object evaluation | CD (× 10^3): 3.92 -> 2.59 | Helped |
| increase spatial resolution from 8×8 to 16×16 (feature dim 2) (ablation) | LAM3D point-cloud compressor · Point cloud to 3D mesh | CD (× 10^4): 4.15 -> 2.12 | Helped |
| increase spatial resolution from 16×16 to 32×32 (feature dim 2) (ablation) | LAM3D point-cloud compressor · Point cloud to 3D mesh | CD (× 10^4): 2.12 -> 1.81 | Helped |
| increase feature dimension from 1 to 2 at 32×32 resolution (ablation) | LAM3D point-cloud compressor · Point cloud to 3D mesh | CD (× 10^4): 1.87 -> 1.81 | Helped |
| increase feature dimension from 2 to 4 at 32×32 resolution (ablation) | LAM3D point-cloud compressor · Point cloud to 3D mesh | CD (× 10^4): 1.81 -> 2.63 | Hurt |
| add the plane refiner (ablation) | LAM3D point-cloud compressor · Point cloud to 3D mesh | CD (× 10^4): 2.37 -> 1.81 | Helped |
| replace ULIP vector feature alignment with LAM3D alignment | Image-to-3D reconstruction · Objaverse 216-object evaluation | CD (× 10^4): 35.23 -> 1.81 | Helped |
Surprising findings
- A deterministic transformer alignment was unstable, so the authors switched to diffusion for probabilistic alignment.
- Replacing the aligned image features in ULIP with a decoder gave much worse Chamfer distance (35.23e-4) than the proposed method, suggesting contrastive alignment is poorly suited to reconstruction.
Limitations
- Only geometry is reconstructed; textured mesh generation is not supported.
- Training is expensive: 32 V100 GPUs for about 3 days in stage 1 and 8 V100 GPUs for 2 days in stage 2.
- Increasing latent tri-plane resolution beyond 32x32 becomes computationally intractable.
Experimental setup
Datasets: Objaverse Google Scanned Objects
Benchmarks: Google Scanned Objects Objaverse (unseen objects)
Metrics: Chamfer Distance Volume IoU F-Score
Baselines: One-2-3-45 LRM / OpenLRM SyncDreamer Wonder3D Magic123 TGS LGM CRM ULIP
Builds on: Large Reconstruction Model (LRM) ULIP DDPM Marching Cubes DINO
Closest papers by meaning
- EdgeMovingNet: Edge-preserving Point Cloud Reconstruction via Joint Geometry Features (CVPR 2025 · similarity 0.88)
- SPAR3D: Stable Point-Aware Reconstruction of 3D Objects from Single Images (CVPR 2025 · similarity 0.87)
- Hyperbolic-Constraint Point Cloud Reconstruction from Single RGB-D Images (AAAI 2025 · similarity 0.86)
- UniPre3D: Unified Pre-training of 3D Point Cloud Models with Cross-Modal Gaussian Splatting (CVPR 2025 · similarity 0.86)
- X-3D: Explicit 3D Structure Modeling for Point Cloud Recognition (CVPR 2024 · similarity 0.85)
- Bridge 2D-3D: Uncertainty-aware Hierarchical Registration Network with Domain Alignment (AAAI 2025 · similarity 0.85)
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